The present invention relates to a method for storing a carrier used in polishing a silicon wafer. In some polishing processes, both surfaces of the wafer are polished simultaneously.
In recent years, attention has been paid to polishing silicon wafers, particularly on both its surfaces simultaneously. However, there is a serious problem of a scratch occurring on the silicon wafer during polishing.
The major cause of the formation of such scratches is attributed to a carrier and a pin sleeve for driving the carrier. Such a carrier and pin arrangement is disclosed in Japanese Patent Application 8-096166. Improvements have been made on these members to reduce the incident rate of scratches.
However, as such improvements proceed, the specifications for allowable scratching have become more restrictive with fewer and smaller being permitted. Thus, even more improvement is needed requiring even stricter controls on the carriers.
Carriers have hitherto been stored in a dry condition, for example, as shown in FIG. 3, where carriers 3 are placed horizontally on a plurality of carrier setters 2 disposed on rollers 4 in a carrier repository 1.
It has been found that because of such dry storage, scratches continue to occur at unacceptable levels. Further, the number of scratches on a silicon wafer increases with the number of times a carrier is used in the polishing process. It is believed that the scratches are caused by contaminants such as residual abrasive slurry on the carriers that become involved with a silicon wafer that is subjected to polishing at the time when a carrier is replaced with a stored one. Contaminants may also become involved as a result of the use of an entirely new carrier.
In view of the aforementioned problems, the present invention aims to provide a method for storing a wafer polishing carrier, which carrier is stored in a manner that will reduce scratches on a silicon wafer which scratches are created during polishing the silicon wafer particularly when polished on both of its surfaces simultaneously.
The present invention provides for a method of polishing a silicon wafer that results in fewer scratches on the wafer; the provision of such a method of using a wafer carrier that can be utilized with current polishing equipment without significant modification; the provision of such a method that is economical to use; and the provision of such a method that can be used in wafer polishing processes that polish both sides of a wafer simultaneously.
The present invention provides a method for storing a carrier used in polishing a silicon wafer. The method includes storing the carrier completely immersed in a liquid containing deionized water prior to use with a wafer in a wafer polishing step.
Other objects and features will be in part apparent and in part pointed out hereinafter.